Entry

Visual Basic .net: Variable: Static: ASP.NET: How create variables which retain their values?

Dec 22nd, 2003 14:18
Knud van Eeden,

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--- Knud van Eeden --- 22 December 2003 - 11:15 pm -------------------

Visual Basic .net: Variable: Static: ASP.NET: How create variables 
which retain their values?

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As variables seemingly are not retained between page loads, you should
put your global variables in the file:

 global.asax

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Steps: Overview:

 1. -Open the file

      global.asax

 2. -Add the declaration of
     your variable at the top of the file
     (and make sure your put it in the class 'Global')

       Public Shared <your variablename> As <your variable type>

     ---

     e.g.

      Public Shared I As Integer

     ---

 3. -Open the file (e.g. webform1.aspx.vb) in which you want to use
     this variable

 4. -To get the value of this variable in your program, use

      Global.<your variable name>

     e.g.

      Global.I

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Steps: Worked out:

 1. -Open the file

      global.asax

 2. -Add the declaration of
     your variable at the top of the file
     (but make sure you add this in the 'Class Global')

      Public Shared I As Integer

 3. -Open the file (e.g. webform1.aspx.vb) in which you want to use
     this variable

 4. -Put a button on this form

 5. -Double click on the button

 6. -Fill in the following code:

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e 
As System.EventArgs) Handles Button1.Click
        Global.rowI = Global.rowI + 1
        Response.Write(Global.rowI.ToString)
    End Sub

 7. -Run the application.

 8. -It will or should now show the number

      1

      2

      3

    ...

    (so an increasing number each time you click on a button)

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THIS BELOW DOES NOT WORK AS EXPECTED, THE VARIABLE VALUE IS *NOT*
RETAINED WHEN YOU CLICK ON THE BUTTON, IT WILL ALWAYS SHOW
THE NUMBER 1 (as it is all the time initialized to 0 when
you click on the button, after which 1 is added)w

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Steps: Overview:

 1. -Open a Microsoft Visual Studio Visual Basic ASP.NET application

 2. -Put a button on the form

 3. -Double click on the button, and add the following text in between:

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e 
As System.EventArgs) Handles Button1.Click

        Static I As Integer

        I = I + 1

        Response.Write( I.ToString )

    End Sub

 4. -Run this application

 5. -When you repeatedly click on the button it will
     not increase the number, so continuously show
     the following number:

      1

      ...

 6. So it keeps the same value between procedure and function calls

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Book: see also:

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[book: Utley, Craig - a programmer's introduction to Visual Basic.NET -
 ISBN 0-672-32203-X - p. 55 'Static not supported on subs or 
functions']

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